1. Field
Exemplary embodiments of the present invention relate to a thin film transistor and a thin film transistor array panel.
2. Discussion of the Background
In general, a flat panel display such as a liquid crystal display, an organic light emitting diode display, or the like includes a plurality of pairs of field generating electrodes and an electro-optical active layer interposed therebetween. The liquid crystal display includes a liquid crystal layer as the electro-optical active layer and the organic light emitting diode display includes an organic emission layer as the electro-optical active layer.
One of a pair of field generating electrodes is generally connected to a switching element to receive an electric signal and the electro-optical active layer converts the electric signal into an optical signal, thereby displaying an image.
In a flat panel display, a thin film transistor (TFT) is a three-terminal element that is typically used as the switching element. The flat panel display also includes signal lines, such as: a gate line that transfers a scanning signal for controlling the thin film transistor and a data line that transfers a signal applied to a pixel electrode.
As display devices become larger, in order to implement high-speed driving, an oxide semiconductor technology has been researched and a method for reducing resistance in signal lines has also been researched.
Recently, a method of replacing known metal wiring material with copper, which has better resistivity characteristics and better electromigration characteristics versus known metal wiring material has been proposed.
However, copper has weak adhesion with a glass substrate and it may diffuse to an insulating layer or a semiconductor layer even at a relatively low temperatures, such as—200° C., thereby making it substantially difficult to apply copper as a single metal wiring material.
Thus, in order to prevent diffusion, a barrier metal layer may be formed between the glass substrate and the gate wiring and between the semiconductor layer and the data wiring, which is a copper wiring structure that is capable of improving an adhesive characteristic and preventing diffusion to the semiconductor layer, has been proposed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.